The present invention relates to a finisher by which an image formed sheet is received, and finishing such as stapling by a stapling means is conducted, after that, the sheets are delivered onto a sheet exit tray, in an image forming apparatus such as an electrophotographic copier, printer, facsimile device or printing machine, and to an image forming apparatus provided with the finisher.
The finisher by which a plurality of sheets, on which images are formed, delivered from the image forming apparatus main body are aligned for each number of copy s, and finishing such as stapling is conducted on the sheets by a finishing means such as a stapling means, is used.
This kind of finisher is connected in its function to the image forming apparatus main body such as a copier, printer, or facsimile device, and is driven corresponding to the sequence operation of copying or printing processes.
Accordingly, for the image forming apparatus main body which can process the image forming process at high speed, the finisher which can performs the function following to the processing speed and can conduct high speed processing, is required.
Such the finisher which can conduct high speed processing, is disclosed already in Japanese Tokkaisho No. 60-142359, No. 60-158463, No. 62-239169, and Japanese Tokkaisho No. 62-288002, No. 63-267667, Japanese Tokkaihei No. 2-276691, and Japanese Tokkohei No. 5-41991.
In the above finisher, the sheets on which images are formed, delivered from the image forming apparatus main body, are successively stacked in the intermediate stacker while being aligned, and after the sheets are accommodated as one package of sheets, finishing by the stapler is conducted on the package of sheets, and stapled package of sheets is placed on an exit belt provided on the bottom portion of the intermediate stacker and conveyed, and nipped by a pair of upper and lower sheet exit rollers and delivered onto a sheet exit tray.
In the sheet exit tray, the sheet placement surface is slantingly arranged in such a manner that the sheet rises toward the leading edge from the trailing edge, and on the back end side of the sheet exit tray, a sheet trailing edge contact reference member is formed such that it is provided vertically. When the trailing edge of the delivered sheet passes on the sheet trailing edge contact reference member, the sheet naturally falls by its self weight, and falls slidingly on the upper surface of the sheets placed on the sheet exit tray, and is brought into contact with the sheet trailing edge contact reference member, thereby, the trailing edge of the sheets is aligned in the sheet exit direction. Such the sheet stacking mechanism is written in Japanese Tokkaisho No. 57-48558.
Th finisher disclosed in Japanese Tokkaihei No. 2-233456 has the sheet exit tray which can horizontally move perpendicularly to the sheet conveyance direction, and the relative position of the sheet exit tray and the delivery position is changed depending on whether finishing is necessary for the sheets.
FIGS. 13(a) and 13(b) show a sheet delivery means of a conventional finisher, and 13(a) is a plan view and 13(b) is a side view viewed from the direction of an arrow A.
The sheet delivered from the image forming apparatus main body is guided into the finisher, conveyed, and aligning processed on the intermediate stacker; after stacked and accommodated package of sheets PTa is stapling processed by the stapling means, the package of sheets PTa is nipped by the rotating sheet exit upper roller R1 and the sheet exit lower roller R2; and its conveyance is assisted by a winding roller R3, the package of sheets PTa is delivered onto an up-and-down sheet exit tray T, and slidingly falls on the slanting surface of the up-and-down sheet exit tray T, or the upper surface of the package of sheets PTb which is already slantingly placed on the up-and-down sheet exit tray T, by the self weight of the package of sheets PTa, and brought into pressure-contact with the outer peripheral surface of the rotating winding roller R3 and conveyed, and brought into contact with a sheet trailing edge contact reference member K and stops.
The leading edge portion of an oscillatable actuator AC to on-, off-operate a sheet exit tray upper limit sensor PS is in light pressure-contact with the upper surface of the package of sheets PT stacked on the up-and-down sheet exit tray T, and corresponding to the height of the sheets stacked on the up-and-down sheet exit tray T, a control means up-and-down controls the up-and-down sheet exit tray T so that the sheet exit lower roller R2 and the upper surface of the package of sheets PT maintain a predetermined interval between them.
When the sheet is delivered one by one onto the slantingly arranged up-and-down sheet exit tray T, because it is difficult that the sheet is assuredly brought into contact with the sheet trailing edge contact reference member K and stopped, only by the self weight of the sheet, sliding contact by the rotating winding roller R3 is necessary.
When the package of sheets, in which a plurality of sheets are stapling processed, is aligned on the up-and-down sheet exit tray T, staple wires stapled onto different positions for each sheet size, come into contact with the sheet exit lower roller R2 or the winding roller R3, and thereby, there is a case that the sheet exit lower roller R2 or the winding roller R3 is shaved and damaged.
In the package of sheets stacking, while the first stapling-processed package of sheets is delivered onto the up-and-down sheet exit tray T, the up-and-down sheet exit tray T is moved below temporarily, and after the first package of sheets PT has been delivered, the up-and-down sheet exit tray T is elevated, and at the time when the sheet exit tray upper limit sensor PS detects the uppermost surface position of the package of sheets PT, the up-and-down sheet exit tray T is stopped, and stands by the sheet exit of the second package of sheets PT.
Conventionally, in the case where, after the stapling is conducted on the sheets, the package of sheets is delivered onto the up-and-down sheet exit tray by the drive of a sheet delivery means, and is brought into contact with a stopper by the winding roller R3 and aligned, when there is a time period of the conveyance interval between respective package of sheets, the up-and-down sheet exit tray is lowered at the time of alignment of the package of sheets, and there is a time margin to stop the drive of the sheet delivery means, and there is no possibility that the staple wires by which the package of sheets is stapled, are brought into contact with the sheet exit lower roller R2 or winding roller R3 and shave them.
That is, in this method, when a large sized sheet (for example, A4R, B4, A3, etc.) or a large number of sheets (for example, more than 3) are stapled, because there is a sufficient time period of the conveyance interval between the first package of sheets and the second package of sheets at the delivery, the up-and-down movement of the up-and-down sheet exit tray T can be conducted.
However, when small sized sheets (for example, A4, B5 sheets) and a small number of sheets (for example, not more than 2 sheets) are stapled, and delivered onto the up-and-down sheet exit tray T by the sheet delivery means and brought into contact with the stopper and aligned, because a time period of the conveyance interval between the first package of sheets and the second package of sheets is greatly small, the drive of the sheet delivery means having the sheet exit upper roller R1 and the sheet exit lower roller R2, and the winding roller R3, is not stopped and the sheet delivery means continues driving-rotation, therefore, the above up-and-down movement of the up-and-down sheet exit tray T can not be applied to it. Therefore, a problem occurs that the staple wires of the stapled package of sheets moving downward on the up-and-down sheet exit tray T shave the surface of the rotating delivery sheet lower roller R2 or winding roller R3, and damage them.
In order to solve the above problems, when the up-and-down sheet exit tray T is lowered from the first, and a predetermined interval is set large, because the interval of the contact pressure position of the sheet exit upper roller R1 and the sheet exit lower roller R2, and the up-and-down sheet exit tray T or the upper surface of the package of sheets stacked on the up-and-down sheet exit tray T, becomes large, the leading edge portion of the package of sheets delivered from the nip position of the sheet exit upper roller R1 and the sheet exit lower roller R2 comes to contact with the up-and-down sheet exit tray T or the upper surface of the package of sheets stacked on the up-and-down sheet exit tray T, and a problem that, as shown in FIG. 13(a), the sheet exit can not be smoothly conducted, is generated.
An object of the present invention is to solve the above problems and to provide a finisher by which, when small sized sheets and small number of sheets are stapled, the prevention of the shaving onto the sheet exit lower roller or the winding roller by the staple wires of the package of sheets, and the control of the upper limit height detection of the up-and-down sheet exit tray for each delivery of one package of sheets, can stand together, and an image forming apparatus provided with the finisher.
(1) The above object can be attained by a finisher, which comprising: a conveyance means for conveying sheets; an intermediate stacker on which conveyed sheets are stacked; a stapling means for stapling a stacked package of sheets; a sheet delivery means for delivering the stapled package of sheets; an up-and-down sheet exit tray on which the delivered package of sheets is stacked and which can move up and down; a driving means for driving the up-and-down sheet exit tray; a detection means for detecting the upper limit position of the uppermost surface of the stapled package of sheets which is stacked on the up-and-down sheet exit tray; and a control means, the finisher being characterized in that: when a mode to staple a package of sheets which is not larger than a predetermined size and not larger than a predetermined number of sheets, is set, the control means temporarily withdraws the up-and-down sheet exit tray from the upper limit to the lower position before the stapled package of sheets has been delivered onto the up-and-down sheet exit tray; and when the drive of the sheet delivery means stops, the control means controls the driving means in such a manner that the up-and-down sheet exit tray is moved upward, and stopped at the upper limit position.
(2) Further, the above object can be attained by an image forming apparatus comprising the finisher described in (1).